Accelerrated C++ Exercise 3-2

#include <algorithm>#include <iostream>#include <vector>using std::cin;using std::cout;using std::endl;using std::sort;using std::vector;int main(){   // ask for and read the integers   cout << "Please enter the integers that are to be "      "end-of-file \"Ctrl+Z\": ";   vector<double> values;   int x;   // values contains all of the integers read so far   while (cin >> x)      values.push_back(x);   typedef vector<double>::size_type vec_sz;   vec_sz size = values.size();   // check that the user entered more than one value, since a   // single value would cause an error   if (size < 2)   {      cout << endl << "You must enter at least two values. "         "Please try again." << endl;      return 1;   }   // sort the values   sort(values.begin(), values.end());   // find the median of the entire set of values   vec_sz mid = size/2;   double median;   median = size % 2 == 0 ? (values[mid] + values[mid-1]) / 2      : values[mid];   // find the size of the lower and upper sets   vec_sz half_size = size % 2 == 0 ? mid : (mid % 2 == 0 ? mid - 1 : mid);   // find the midpoint of the lower and upper sets   vec_sz half_mid = half_size / 2;   // find the median of the lower set, which is the lower quartile   double lower_quartile;   lower_quartile = half_size % 2 == 0 ? (values[half_mid] + values[half_mid-1]) / 2      : values[half_mid];   // find the median of the upper set, which is the upper quartile   vec_sz upper_mid = size % 2 == 0 ? half_size + half_mid : half_size + half_mid + 1;   double upper_quartile;   upper_quartile = half_size % 2 == 0 ? (values[upper_mid] + values[upper_mid-1]) / 2      : values[upper_mid];   cout << "The quartiles are " << lower_quartile << ", "<< median << ", and " << upper_quartile << endl;   system("pause");   return 0;}